1. Field of the Invention
The invention relates to a wireless local area network (WLAN), and more particularly to radar detection required for high-speed WLANs in regulatory frequency ranges.
2. Description of the Related Art
Recent approval of the IEEE 802.11 standard for wireless networking and rapid progress toward higher data rates have positioned this technology to fulfill the promise of truly mobile computing. IEEE 802.11, part of a family of standards for local and metropolitan networks, defines wireless LAN media access control (MAC) and physical layer (PHY) specifications. In addition to the base standard, IEEE 802.11a is a supplement defining the high-speed PHY in the 5 GHz band, and IEEE 802.11h is another supplement for spectrum management in the 5 GHz band in Europe.
The 5 GHz band in Europe refers to the nineteen 20 MHz channels between 5 GHz and 6 GHz in which WLAN operation is allowed in the regulatory frequency bands ranging from 5.15˜5.35 GHz and 5.47˜5.725 GHz. According to ERC Decision of 29 Nov. 1999 made by European Radiocommunications Committee, WLANs (a.k.a. radio LANs, RLANs) operating in the 5 GHz band are required to implement a mechanism to avoid co-channel operation with radar systems and to ensure uniform utilization of available channels. Therefore, RLAN equipment conforming to the IEEE 802.11h standard must employ a Dynamic Frequency Selection (DFS) mechanism to detect interference from other systems and to avoid co-channel operation with other systems, notably radar systems. However, the methods to detect radar operation in a channel that satisfy regulatory requirements are not defined in IEEE 802.11h.
Accordingly, what is needed is an efficient method of radar detection to meet requirements in some regulatory domains for operation in the 5 GHZ band.